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Assignees
MemberJohns Hopkins UniversityJohns Hopkins UniversityFounded in 1876, Johns Hopkins University is recognized as the first research university in the United States. It advances interdisciplinary education, high-impact research, and global outreach, supporting knowledge translation, technological innovation, and community partnerships. The university fosters academic excellence, innovation incubation, outreach, and inclusion across multiple campuses in Baltimore, integrating into the city's social, economic, and cultural life.
Founded in 1876, Johns Hopkins University is recognized as the first research university in the United States. It advances interdisciplinary education, high-impact research, and global outreach, supporting knowledge translation, technological innovation, and community partnerships. The university fosters academic excellence, innovation incubation, outreach, and inclusion across multiple campuses in Baltimore, integrating into the city's social, economic, and cultural life.
Publication Number
US-12661056-B2
Publication Date
2026-06-23
Expiration Date
Abstract
A sweat sensor includes a first conductor and a second conductor that are parallel with one another. The sweat sensor also includes a channel disposed between the first and second conductors. The channel is configured to receive a sample of sweat. A measure of capacitance between the first and second conductors changes based at least partially upon a volume of the sweat in the channel.
Core Innovation
The invention relates to a capacitive sweat-rate sensor that includes metallic plates arranged in parallel and a supporting layer positioned between the plates. The supporting layer defines a channel configured to receive a sample of sweat, and the capacitance between the conductors changes based at least in part on a volume and/or rate of the sweat in the channel.
The sensor further specifies a layered structure in which bottom and top insulating layers define an inlet and an outlet and a microfluidic channel in fluid communication with the inlet. Conductive bottom and top plates are parallel with one another, and the supporting layer is positioned above the bottom plate and defines the channel.
In additional embodiments, the sensor includes impedance electrodes positioned on opposite sides of the channel such that sweat is contacted by the electrodes. The circuit measures an impedance between second and third electrodes and determines a conductivity of the sweat based at least partially upon the impedance.
Claims Coverage
The partial content contains three independent claims. Across them, the inventive features focus on a stacked sweat-channel sensor with parallel conductive plates, a supporting layer that defines a sweat channel, and a circuit that determines sweat rate from capacitance while additional electrodes enable sweat conductivity determination from impedance.
Parallel conductive sweat-channel capacitance sensor
A sweat sensor comprising a first conductor and a second conductor in metallic plates that are parallel with one another, and a supporting layer positioned between the first and second conductors, wherein the supporting layer defines a channel configured to receive a sample of sweat and wherein a measure of capacitance between the first and second conductors changes based at least partially upon a volume and/or rate of the sweat in the channel.
Layered inlet-outlet capacitive rate determination
A sweat sensor comprising a bottom insulating layer defining an inlet configured to receive sweat, a bottom plate positioned above the bottom insulating layer, and a supporting layer positioned above the bottom plate, wherein the supporting layer defines a channel in fluid communication with the inlet; a top substrate and a top plate positioned above the supporting layer, wherein the bottom plate and the top plate comprise a conductive material and are parallel with one another; a top insulating layer defining an outlet in fluid communication with the channel; and a circuit configured to measure a capacitance between the bottom plate and the top plate using a first electrode and determine a rate of the sweat based at least partially upon the capacitance.
Simultaneous sweat rate and conductivity using capacitance and impedance
A sweat sensor comprising a bottom insulating layer defining an inlet configured to receive sweat from a user's skin and defining a channel configured to receive the sweat, a bottom plate and a top plate comprising a conductive material and being parallel, and a circuit configured to measure a capacitance between the bottom plate and the top plate using the first electrode and determine a rate of the sweat based at least partially upon the capacitance, and further measure an impedance between the second and third electrodes and determine a conductivity of the sweat based at least partially upon the impedance.
Overall, the independent claims cover a sweat sensor with a supporting layer forming a sweat channel between parallel conductive plates, using a first electrode to measure capacitance and determine sweat rate, and in further embodiments adding second and third electrodes to measure impedance and determine sweat conductivity.
Stated Advantages
Enables determination of a rate of the sweat based at least partially upon the measured capacitance.
Enables determination of a conductivity of the sweat based at least partially upon the measured impedance.
Enables simultaneous determination of the sweat rate and the sweat conductivity.
Documented Applications
Wearable trials including pilocarpine iontophoresis and exercise for monitoring and correlation/calibration consistency of sweat sensing.
Measurement of sweat conductivity in addition to sweat rate via integrated impedance electrodes.
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